1. Field of the Invention
The present invention relates to skin peels utilizing alpha and beta hydroxy or keto acids as a topical treatment for hyperpigmentation, melasma, dyschromia, rhytides, photodamage and aging. Preferred peels contain alpha and beta hydroxy or keto acids with kojic acid or its derivatives in a dermatologically acceptable carrier such as an ethanoic/water mixture. Optionally, hydroquinone or its derivatives and other skin lighteners may also be employed in the peel when conditions warrant.
2. Description of Related Art
Skin peels are classified into three general types: light or superficial, medium and deep.
The deep peel utilizes phenol as a primary ingredient. Phenol (C.sub.6 H.sub.5 OH) obtained from coal tar and also called carbolic acid was first described as a peel in 1882 by the German dermatologist Dr. P. G. Unna. In 1903, Dr. G. M. Mackee, a British dermatologist began using phenol peels for acne scarring. Phenol peels were used as a treatment for gunpowder burns of the face in World War I. In the 1930s and 40s Antoinette la Gasse used phenol peels to improve scarring and wrinkles in a Los Angeles salon. Dr. J. C. Urkov described a phenol peel under occlusion as a method for wrinkle treatment in 1946. In the 1960s, Dr. Adolph Brown, a maxillofacial surgeon, and his wife, Dr. Martha Brown, a dermatologist, performed detailed studies on phenol peel formulas and toxicities that resulted in a renaissance in phenol peeling. Dr. F. C. Combes and Dr. P. A. Sperber devoted considerable effort to developing a buffered phenol peel that would be less caustic than the extremely harsh full strength phenol peels. Also in the early 1960s, Dr. Thomas M. Baker collaborated with Dr. H. L. Gordon to develop a saponated phenol peel that is still in use today.
Phenol peels penetrate as far as the mid-reticular dermis and cause virtually complete necrosis of the epidermis and the papillary dermis that extends into the reticular dermis. Phenol is directly toxic to the myocardium and cardiac arrhythmias have been reported with many phenol peels. If a high dose is used they are also hepatotoxic and nephrotoxic. Certain predisposed individuals may experience idiosyncratic cardiac death from an adrenalin release due to facial pain transmitted from the trigeminal nerve to the cardiac vagal nerve or from the cerebral cortex directly to the cardiac sinoatrial node. The possibility of complications from the aforementioned deep phenol peels is significant. Hypertrophic, atrophic and keloidal scarring were reported by 21% of 588 plastic surgeons surveyed in a 1981 report in the journal of Plastic and Reconstructive Surgery. Other possible complications of the phenol peels include adverse textural changes to the phenol peeled skin and infectious conditions such as bacterial pyoderma, toxic shock syndrome, herpes simplex virus, and Epstein-Barr virus keratitis. Unsightly pigmentary occurrences that may result from the said phenol peels include hyperpigmentation, hypopigmentation, porcelain depigmentation, visible lines of demarcation with unpeeled skin and nevi accentuation.
Phenol peels are outside the realm of utilization of the present invention and from the aforegoing description of the possible adverse results elicited by the use of the said phenol peels it should be readily apparent that safe, efficacious peels such as the present invention have great utility in dermatologic practice.
Medium depth peels are defined as those that penetrate to the upper reticular dermis. The most commonly used medium depth peel is the 40% to 60% trichloroacetic acid peel. The German dermatologist, Dr. P. G. Unna, first employed trichloroacetic acid as a peeling agent and described his technique in 1882. Dr. S. Monash conducted experiments with trichloroacetic acid peeling and published a paper entitled "The uses of diluted trichloroacetic acid in dermatology" in 1945. Dr. S. Ayres combined the trichloroacetic acid peel teachings of Dr. S. Monash with his own conclusions based on clinical experience and published two papers relating to trichloroacetic acid peeling in the early 1960s. Dr. S. S. Resnik, Dr. L. A. Lewis and Dr. B. H. Cohen published the paper "Trichloroacetic acid peeling" in the journal Cutis in 1976. Dr. S. J. Stegman's histologic findings with trichloroacetic acid peeling in the early 1980s began efforts to investigate skin peeling in a controlled and scientific manner. Dr. Harold J. Brody and Dr. C. W. Hailey published "Medium depth peeling of the skin" in the Journal of Dermatologic Surgery and Oncology in 1986. Dr. Gary Monheit pioneered combination peels by combining the trichloroacetic acid peel with the superficial peel utilizing Dr. Jessner's solution and published "The Jessner's + TCA peel" in the Journal of Dermatologic Surgery and Oncology in 1989. The most recent developments in trichloroacetic acid peeling are found in the "Manual of Chemical Peels: Superficial and Medium Depth" by Dr. Mark G. Rubin. U.S. Pat. No. 4,874,361 and U.S. Pat. No. 5,166,176 issued to Dr. Zein E. Obagi and Dr. George H. Michel describe the use of trichloroacetic acid peels in combination with surfactants, humectant-emollients and emulsifiers for healing damaged skin.
Medium depth peeling with trichloroacetic acid does not require hospital care and general anesthesia as the phenol deep peels do, nor is there near the number of possible complications and adverse results, however, there is a significant risk of scarring at high concentrations of trichloroacetic acid. The present invention is quite suitable as a pretreatment for the trichloroacetic acid peels and may reduce the concentration requirements while still obtaining comparable results.
Superficial peels, as in the case of medium and deep peels, were pioneered by the German dermatologist, Dr. P. G. Unna, and the use of salicylic acid and resorcinol as superficial peeling agents were described by Dr. Unna in 1882. In the 1930s a superficial peel containing resorcinol, salicylic acid, lactic acid, oil of rose and ethyl hydrate was utilized and this peel was reported by Dr. J. J. Eller and Dr. S. Wolff in their article "Skin Peeling and Scarification" in the Journal of the American Medical Association in 1941. A superficial peel comprised of resorcinol, salicylic acid, and lactic acid was reported on by Dr. F. C. Combes, Dr. P. A. Sperber and Dr. M. Reisch. Essentially the same superficial peel was commented on in the paper "The light peel" in the Bulletin of the Association of Military Dermatologists by Dr. P. N. Horvath in 1970. The prominent dermatologist, Dr. Max Jessner, extensively applied this same superficial peel on many patients to the extent that to the current time this superficial peel is known to over 40,000 United States dermatologist as the Jessner's solution and as the Combes' Peel or Horvath's Concoction. Prior art contains U.S. Pat. No. 4,608,370 issued to Richard B. Aronsohn, a California dermatologist relating to a skin formulation which is in essence merely a diluted version of the superficial peel described in the literature. The present invention in its various embodiments successfully replaces the Jessner's Solution, Combes' Peel and Horvath's Concoction used by United States dermatologists for the last 60 years because of the present invention's improved biocompatability, higher efficacy and wider versatility over the range of skin complaints exhibited to the dermatological practitioners.
Superficial peels range in depth from the stratum granulosum to the upper papillary dermis depending on formulation, technique and patient skin type. Complications with superficial peels are few and mild if experienced. Weekly or monthly superficial peels may be performed to achieve results more comparable with the deeper peels.
None of the prior art, to applicant's knowledge, discloses a superficial peel utilizing alpha and beta hydroxy or keto acids with kojic acid or its derivatives to treat photodamage, rhytides and pigmentary dyschromias.
Further, prior art relating to therapeutic skin peeling does not disclose use of citric acid, a major component of the Kreb's cycle, tricarboxylic acid cycle or citric acid cycle as it is variously referred to in mammalian metabolism.
Whereas prior art does not contain disclosure of the fungal metabolite kojic acid or its derivatives widely known as skin lighteners in any skin peel of any depth their utilization as skin peel components may be considered novel.
An object of the invention in its various embodiments is to provide the practicing dermatologist with an array of superficial peels capable of addressing a wide variety of functional and cosmetical skin defects as might be encountered in everyday practice without significant irritation or complication.
It is another object of this invention to provide a safe and efficient peel in the treatment of regional hyperpigmentation caused by melanocytic hyperactivity, such as idiopathic melasma occurring during pregnancy or melasmas secondary to estrogen-progesterone contraception. The peels of the present invention are also effective for localized hyperpigmentation and benign melanocytic proliferations, such as senile pigmentary spots, actinic photosensitization and post-lesion scarring.
It is still another object of this invention to provide a selection of peels beneficial in the treatment and prevention of acne.